Commando gaskets

Hi All. I bought a gasket set through the NOC . The base gasket has just failed at the driveside rear. This had been replaced about 2000 miles ago, so not happy. Everything was tight, I think the gasket was made out of a red material same as my valve cover gaskets which do seem to be a bit soft/gooey. I'm sure I read somewhere that these gaskets are shit, I 've sent an email to NOC to see what they say. On another note, when I removed the head, I noticed that the oil drain hole at the rear was partially covered (50%. composite gasket, the holes had also elongated.) All the fixings were tight, I had also gone through the tightening procedure as defined in the bible.

Any ideas why?

Thanks
Paul

I usually get my gaskets from AN , but I did buy some from NOC recently but have not used any ,so couldn't give you any feedback . Sorry to hear about your probs , but I can't believe Neil would intentionally sell poor goods.

Jg

I got sick of base gaskets blowing out. No gasket this time, just sealant. Problem solved.

I have installed base gaskets twice on my '74 Commando and once on my Mercury. I used gaskets sourced from Andover/Norton.
Never once has any hint of oil seeped from these. I do tighten them to spec, ride a few hundred miles and then torque to spec again.
I expect that, if there is a next time, I will not use a gasket at all.

I left out the base basket. Partly as I was worried about failure. Partly as I was worried the gasket might compress slightly, making the through bolts lose torque and they are inaccessible to tighten. And partly as I wanted the slight CR boost.
I use wellseal jointing compound.
I've had zero leaks or issues.

I have always found that, on a 750 at least, the base nuts on the barrel need a couple of rounds of tightening after a couple of heat cycles subsequent to replacing this gasket.

I used to find the paper ones would continually compress and I would be tightening the base nuts quite frequently.
I now use a copper base gasket from Jim Schmidt. Problem solved.

Fast Eddie said:

I left out the base basket. Partly as I was worried about failure. Partly as I was worried the gasket might compress slightly, making the through bolts lose torque and they are inaccessible to tighten. And partly as I wanted the slight CR boost.
I use wellseal jointing compound.
I've had zero leaks or issues.

Click to expand...

Cheers Eddie. Yes I think I'm going down that route.

Paul.

If I omit the base gasket on my Mk3, will the pushrods have to be shortened? Any other problems to consider?
Thanks,
Jaydee

I think you ought to be careful not putting a gasket back on a used engine. The rings do wear into the bores and a lip starts occurring. No gasket means the rings will have to ride over this lip. Need I say what might happen.

I once used a blue/green coloured gasket on my gearbox outer cover. It went soft and shit itself at a rally once. I now make my own gaskets for the g/box [ just like the old days with the brown gasket material. I bought several sheets of differing thicknesses and sealed them up in a zip-lock bag to keep them soft ] . I have bought all my cylinder base gaskets from British Spares and have never had a problem so far.

As for using shorter push rods. Yes if you want perfection. the rockers are designed to be at right angles to the valve stem 1/2 way through the stroke. lowering the barrel will mean the push-rods will be at right angles to the valve stem somewhere before the 1/2 way point, and will tend to pull the valve in towards the centre of the head more at the end of the travel, than should happen.

Dereck

Not sure what model Commando you have but in the workshop manual it say on the 750s to not use a base gasket and replace with a good sealant, so for the last few rebuilds I used the same sealant as I use on the crank halfs, in the book it explains that the base gaskets moves and thats one of the reasons the gasket fails, I have rebuilt 5 Commando motors now (2 750s and 3 850s) without using a base gasket including my own motor and have had no problems at all with leaking.

Ashley